Several laboratories are developing mechanical circulatory support systems (MCCSs) with financial support from the NHLBI and private support. The new generation of MCCSs will be electrically actuated by means of percutaneous leads or transcutaneous energy transmission systems (TETS). This proposal describes a TETS already operating at 86% DC to DC efficiency at an output power of 60 Watts. This high efficiency was made possible by the discovery of a novel tuned rectifier which operates to convert radio frequency power to direct current. An important benefit of this design is a significant reduction in the radio frequency current which circulates in the internal induction coil. The reduced current has a major impact in reducing heat generated by the internal coil which has at times caused necrosis in the coil region. It is proposed that work on the TETS be continued with the addition of a feedback control system for control of output voltage based on a novel load modulation approach. The load modulation scheme described in this proposal would operate independent of any data communication system and mark a key step in the development of an efficient alternative to percutaneous leads. It is anticipated that efficiency can be improved to the 88 to 90% range by making some improvements in the implementation of the tuned rectifier. PROPOSED COMMERCIAL APPLICATION: NOT AVAILABLE